The Chelsea owner's vessel had been the world's biggest yacht – until Azzam's launch in Germany yesterday.

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For the playboy who has everything: Azzam the £400m superyacht blows everything else out of the water

Ownership of the £400million craft is
shrouded in secrecy but it is rumoured to have been paid for by a member
of the Saudi royal family, Alwaleed Bin Talal Alsaud.

Longer than 12 double-decker buses,
not only is Azzam the biggest superyacht, it is also expected to be one
of the fastest. The 94,000 horsepower vessel could reach speeds of more
than 30 knots, or 35mph.

The size of superyachts has grown as
billionaires compete to own the largest and its builders boast that
Azzam, which means dedication in Arabic, is the 'most complex and
challenging yacht that has ever been built'.

Little is known about the interior of
the yacht, which will require a staff of 50 and will be delivered to its
owner later this year.

But it is likely to match the luxury
of Abramovich's Eclipse, which features an armour-plated master suite,
two swimming pools, two helipads, a hall, a cinema, a mini-submarine and
even its own missile defence system.

Longer than some cruise ships: Azzam is described as the 'most complex and challenging yacht' ever built

No expense spared: New super-yacht Azzam has taken one year to design and three years to build

Abramovich has owned Eclipse, which is
valued at £740million, since it was launched in 2010. It took the title
of world's biggest private yacht from the 454ft Rising Sun, owned by
American businessman Larry Ellison, which in turn took over from the
414ft Octopus, owned by Microsoft co-founder Paul Allen.

Prince Alwaleed, who is said to be
worth around £10billion, already has Nabil, a yacht formerly owned by
Saudi Arabian arms dealer Adnan Khashoggi, in his fleet.

If he is confirmed as the owner of Azzam, it will be the second time the 58-year-old has got the better of Abramovich.

The 46-year-old Russian was denied a
berth at Antibes harbour on the French Riviera in 2011 as the prince had
docked another of his yachts, the 265ft Kingdom 5KR, in the last
remaining space.

Eclipse's crew pleaded for a berth but
were eventually forced to drop anchor at sea and travel to the
Russian's villa on a motorboat.

Azzam's design suggests it has been
built for a buyer in the Middle East as it has about 50 suites but no
large open spaces on deck, said TheYachtPhoto's Peter Seyfferth.

'I have never seen an Arab-owned yacht with big parties and girls round the pool like the Russians have,' he said.

'It is unlikely it will leave its dock very often. It is more of a question of prestige, to have the world's largest yacht.'